Assessment of water supply system and water quality of Lighvan
village using water safety plan
Mojtaba Pourakbar1, Mohammad Mosaferi2*, Saeed Lak3
1MSc of environmental health engineering, Department of Environmental Health Engineering, Faculty of Health, Tabriz University of Medical Sciences, Tabriz, Iran
2Professor, Tabriz Health Services Management Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
3MSc Student of Environmental Health Engineering, Department of Environmental Health Engineering, Faculty of Health, Ardabil University of Medical Sciences, Ardabil, Iran
Abstract
Background: Continuous expansion of potable water pollution sources is one of the main concerns of water suppliers, therefore measures such as water safety plan (WSP), have been taken into account to control these sources of pollution. The aim of this study was to identify probable risks and threatening hazards to drinking water quality in Lighvan village along with assessment of bank filtration of the village.
Methods: In the present study all risks and probable hazards were identified and ranked. For each of these cases, practical suggestions for removing or controlling them were given. To assess potable water quality in Lighvan village, sampling was done from different parts of the village and physicochemical parameters were measured. To assess the efficiency of bank filtration system of the village, independent t test was used to compare average values of parameters in river and treated water.
Results: One of the probable sources of pollution in this study was domestic wastewater which threatens water quality. The results of this study show that bank filtration efficiency in water supply of the village is acceptable.
Conclusion: Although Bank filtration imposes fewer expenses on governments, it provides suitable water for drinking and other uses. However, it should be noted that application of these systems should be done after a thorough study of water pollution level, types of water pollutants, soil properties of the area, soil percolation and system distance from pollutant sources.
Keywords: Bank filtration, Lighvan, Risk ranking, Water safety plan, Water pollution
Citation:Pourakbar M, Mosaferi M, Lak S. Assessment of water supply system and water quality of Lighvan village using water safety plan. Environmental Health Engineering and Management Journal2015; 2(4): 187–192.
*Correspondence to: Mohammad Mosaferi Email: mmosaferi@yahoo.com Article History:
Received: 8 August 2015 Accepted: 23 November 2015
ePublished: 9 December 2015
Introduction
Safe drinking water is one of the necessities to sustain life and a satisfactory (adequate, safe and accessible) supply of water must be available for all peoples. Qualitative assess-ment of water leads to improveassess-ment in water quality and is an important factor in water treatment (1).
Although two-thirds of the earth is covered with water, available fresh water is rare. Along with water scarcity, water pollution is the other issue threatening fresh water resources (2,3).
Industrialization without considering sustainable de-velopment principles, population increase, modern and mechanized agriculture, etc have contributed to the pollu-tion of water resources in recent years. This is much more significant especially in the case of developing countries (4,5).
In some villages in the country, domestic sewage flows through streets and open canals. This kind of wastewa-ter collection leads to the contamination of surface and groundwater. Also, leachate with lots of nitrogen and mi-croorganisms are the other source of pollution. Typically, these sources of pollutants are source of pathogenic con-tamination for drinking water.
Over time and with increased attention to the quality of drinking water during the last few years, different meth-ods have been used to assess the quality of drinking water resources. Such measures over the last few years in rela-tion to drinking water in the world is the implementa-tion of water safety plans (WSPs). Given the importance of access to safe water, WSP since 2004 has been on the agenda of the World Health Organization (WHO) (4,6-8). Monitoring and evaluation of water from catchment to the
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Original Article
consumption point is taken into consideration, and study programming is reached as shown in Figure 1 (7). The primary objectives of a WSP in ensuring good drink-ing-water supply practice are the prevention or minimi-zation of contamination of source waters, the reduction or removal of contamination through treatment processes and the prevention of contamination during storage, dis-tribution, and handling of drinking water. A WSP has three key components which are; system assessment, op-erational monitoring and management and communica-tion plans (7).
Lighvan is a village in Meydan Chay rural district, in the central district of Tabriz county, East Azerbaijan province, Iran. At the 2011 census, its population was 5524, in 1553 families (9).
It is famous for its slight weather during summer time and cold weather in winter. The main occupation of the people is agriculture, dairy and gardening. Lighvan’s traditional feta cheese is the most famous cheese all around Iran. To our knowledge, there is no study about the quality of drinking water supply in Lighvan village and assessment of the village system performance. Therefore, the present study was aimed to identify risks and hazards threatening water quality and health of the villagers and to prioritize and monitor the risks and hazards. The performance of the river bank filtration (RBF) of the village was also in-vestigated.
Methods
Before 2004, drinking water in Lighvan village was
pro-Figure 1. “Catchment to consumer” approach to risk management of the safety of the drinking water.
Table 1. Scoring matrix for ranking risksa
Likelihood Severity of consequences
Insignificant Minor Moderate Major Catastrophic
Almost certain 5 10 15 20 25
Likely 4 8 12 16 20
Moderately likely 3 6 9 12 15
Unlikely 2 4 6 8 10
Rare 1 2 3 4 5
aRisk rating: Low, <6; Medium, 6-9; High, 10-15; Very high, >15.
vided only from the spring. This spring was sanitized 20 years ago. The source of the water to this spring is pro-vided from RBF. In recent years, the RBF system could not solely provide water for the village due to population in-crease in the village. In 2004, a well was drilled to a depth of 160 meters on the south side of the village. Well water after disinfection with chlorine along with RBF water are pumped to a storage tank on top of a mountain overlook-ing the village from where the water is injected to the wa-ter distribution network of the village.
In this study (conducted in 2014), the first step was to identify the hazards and potential risks in different parts of the water distribution network and prioritize them. A variety of different semi-quantitative and qualitative ap-proaches have been proposed for ranking risks. In this study the ranking proposed by the WHO was used. The semi-quantitative approach used in the present study is shown in Table 1 (9).
The study identifies and prioritize the risks in accordance with the above matrix and then strategies to modify or re-duce the risks were also presented.
Lighvan river originates from the northern slopes of Sa-hand mountain. Several springs and rivers join to form the Lighvan river. The river flows from south to north and irrigates downstream lands. This river flows in relatively deep valley in the downside of the village.
In this study, 3 water samples from different parts of the river flowing through the village were taken. The samples were taken from entrance, middle (next to RBF system), and the lower course of the river in village. Parameters including pH, electric conductivity (EC), hardness, ma-jor cations (Ca2+, Mg2+, Na+ and K+) and major anions
(HCO3−, SO
42−, Cl−, F− and NO32−) were measured. All the
analyses were done according to standard methods for ex-amination of water and wastewater (10).
In order to study the performance of the filtration system of the village and impact of the river water on the treated water by RBF, statistical analysis was used. To assess the normality of the variables in spring and summer seasons, Kolmogorov–Smirnov test was used and confirmed. For the comparison of mean values of the indices, indepen-dent t test was used. P < 0.05 was considered significant.
Results
Potential hazards
All potential risks of water quality of Lighvan village are shown in Table 2. Likelihood and severity of each of the risks was determined by 3 environmental health experts
and finally the extent of these risks was ranked.
As indicated in the table, the sanitary wastewater of the village is one of the main potential source of pollution. This is particularly important in the case of RBF.
Physicochemical analysis of water samples
Results of the physicochemical analysis are presented in Table 3. In terms of hardness, water is grouped as soft water (<75 mg/L CaCO3), medium hard (75–150 mg/L CaCO3), hard water (150–300 mg/L CaCO3) and very hard water (>300 mg/L CaCO3). As specified in the table, the range of total hardness in the network water samples was 124-136 mg/L CaCO3, indicating that the studied
wa-Figure 2. Sampling points and RBF system of the village. Figure 3. Piper diagram for the analyzed samples.
Table 2. Potential pollution risks ranking
Event Likelihood Severity Risk ranking
Contamination of drinking water by sanitary wastewater discharged to river 5 4 20
Drinking water contamination by sewage from dairy products canters, especially in the months of
January through the end of July 3 3 9
Drinking water contamination by animal waste 4 2 8
Drinking water contamination by agricultural drainage 3 2 6
The risk of secondary contamination due to lack of residual chlorine in the network 2 2 4
Contamination of drinking water by the wastewater from nearby school 2 1 2
Table 3. Mean values of physicochemical analysis of water samples
Sample pH µs/cmEC mg/lTDS Turbidity NTU mg/lF mg/lCl SO4
mg/l mg/lNO3 mg/lCa mg/lMg mg/lNa mg/lK Hardness mg/l Alkalinity mg/l
Network 1 7.20 320 208.0 0.21 0.6 36 23.8 9.4 35.2 9.7 30.0 4.2 128 112
Network 2 7.02 315 204.8 0.34 0.6 36 25.5 7.4 41.6 7.8 28.9 4.1 136 112
Network 3 7.12 318 206.7 0.39 0.6 36 26.1 7.2 36.8 7.8 31.2 4.2 124 112
RBF 7.03 310 201.5 0.26 0.6 32 32.5 8.5 35.2 8.7 31.2 3.9 124 116
Well 7.02 340 221.0 1.16 0.6 36 35.2 7.3 36.8 10.7 35.8 4.1 136 128
River 3 7.35 360 234.0 20.40 0.6 44 41.1 6.9 30.4 11.7 47.3 4.2 124 112
River 2 7.60 335 217.8 12.60 0.6 42 38.9 4.2 27.2 12.6 41.5 3.5 120 108
ter samples could be grouped as medium hard water. Elec-trical conductivity was almost same in different parts of the water distribution network, indicating that there is no change in dissolved solids.
As shown in Table 3, the amount of dissolved solids in the RBF is less compared to the well.
Figure 3 shows the piper diagram for samples taken from the Lighvan village. As shown, samples taken from drink-ing water contains higher bicarbonate ions compared to samples taken from the river.
Figure 4 shows the stiff diagram of the water samples for network, river, spring and well. As shown in the figure, sodium and chloride in the river water is higher than in
drinking water. The type of river water is sodium-bicar-bonate, while it is calcium-bicarbonate for drinking water.
Evaluation of river bank filtration system performance
RBF is a type of filtration that works by passing water to be purified for use as drinking water through the banks of a river. Schematic diagram of Lighvan village RBF is illustrated in Figure 5. As shown in the figure, water passes through river bank and then, the purified water is taken for drinking purpose. After passing the river water through the RBF, reduction was observed in pH, turbidity, total dissolved solids (TDS), magnesium, sodium, sulfate and chloride. However, there was a slight increase in bi-carbonate, potassium, nitrate, calcium and hardness. The results of P value between the mean values of the physicochemical parameters of the river and RBF system shows that there is only significant correlation between chloride (P = 0.049) and magnesium (P = 0.032). Discussion
One of the main problems that threaten the safety of the village water is sanitary wastewater and the wastewater discharged to the river from dairy production centers. Considering that a large population inhabits the village, thus a large amount of wastewater is produced. The in-trusion of wastewater to the river and passage through the RBF could threaten public health of the villagers. It is strongly suggested to modify the wastewater collection network of the village and to channel the collected waste-water downstream of the village. Then it could be treated by natural wastewater treatment systems, and after being purified up to an accepted level it could be discharged to the river. Minimal corrective action which could be given should be that discharge of wastewater to the river from the upstream of the RBF should be stopped.
About the case of animal wastes, which could be the main reason for an increase in nitrate concentration of the RBF effluent, it is suggested to allocate some sites out of the vil-lage for waste storage.
It is suggested to construct special canals for collecting agricultural drainage particularly near the well and RBF system.
About the case of river water quality, due to the intrusion of wastewater, the amount of dissolved solid increases in the river water on passing through the village. As previ-ously mentioned, there are lots of diary production cen-ters in the village, these cencen-ters also discharge their waste-water, which contains high amount of salt (salt is used for preservation of cheese) into the river.
According to the lithology maps of the studied area, geo-logical structure of the village is made of volcanic and sedimentary rocks. Based on the results of the present study, bicarbonate and calcium of the water increase after passing through the RBF. This could be attributed to the geological structure of the study area which is made up of volcanic and sedimentary rocks (Eq. 1) (11).
Figure 4. Stiff diagram for the analyzed samples.
CaCO3 + H2CO3 → Ca2+ + 2HCO 3 (1)
As shown in Table 3, potassium was also increased in the water on passing through the RBF system, which was also observed in groundwater. This could be due to the pres-ence of potassium-feldspar minerals in the geological structure of the area. Potassium-feldspar can react with carbonic acid and generate potassium and increase alka-linity as shown in Eq. 2 (12).
2 3 3 8 2 3 2 4 4
H CO KAlSi O H O+ + →K++HCO−+ H SiO (2)
Subsurface water storage systems have the advantages of natural capacity of water and soil therefore, in addition to little cost to governments, it can generate high quality wa-ter (13-15). In this study some chemical paramewa-ters such as hardness, alkalinity, nitrate, potassium and calcium increased after treatment which is similar to the findings of a study conducted in Egypt on the Nile River filtration system. However, the amounts of magnesium, sodium, sulfate and chloride decreased which contrasts the find-ings of the Nile River study. In addition, similar to the study in Egypt, turbidity and amount of suspended solids reduced significantly (16).
Although nitrate was low, it increased after passing through the filtration system. This could be due to ac-cumulation of animal waste near the RBF system which leads to the filtration of nitrogen from animal waste into treated water.
In general, in the construction of these kinds of systems, there should be much emphasis on water pollution, type of pollutant, soil type, soil permeability and the distance of the system from pollution sources. While this method is recommended for use in different parts of Iran, com-prehensive studies in this field is also proposed for accu-rate and continuous monitoring of water for chemical and biological parameters before and after construction of the system and during its operation.
Conclusion
Many risks and hazards of pollution could be controlled by implementation of rural WSP. Therefore, implementa-tion of these kinds of programs, especially in rural com-munities is recommended.
Although bank filtration imposes fewer expenses on gov-ernments, it provides suitable water for drinking and other uses. However, it should be noted that application of these systems should be done after a thorough study of water pollution level, types of water pollutants, soil properties of the area, soil percolation and system distance from pol-lutant sources.
Acknowledgments
This article was a report from the data obtained during a MSc thesis, registered in Tabriz University of Medical Sci-ences (TBZMED). We also appreciate the Environmental
Chemistry Laboratory of the Faculty of Health, especially Mr. Mohammad Abedpour.
Ethical issues
It is confirmed that this manuscript is the original work of the authors and has not been published or under review in another refereed journal, and is not being submitted for publication elsewhere.
Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
All authors contributed equally and participated in the data collection, analysis and interpretation. All authors critically reviewed, refined and approved the manuscript.
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